1. Field of the Invention.
The present invention is an electronic system for identifying the location of personnel within a multiple room complex. In particular, the present invention is an ultrasonic personnel location identification system utilizing pulse code modulated transmissions.
2. Description of the Prior Art.
In large multiple room complexes it is often desirable to identify the location of various persons within the complex. In a hospital ward, for example, it is often important for a head nurse or other attendant at a central station to know in which rooms various types of personnel such as other nurses or aides are located.
Personnel location systems of the type discussed above are well known and widely used in hospitals. One such system includes switches in each room which are actuated by a nurse and/or aide when they enter the room. The switches are interfaced to the central nursing station which provides an indication of personnel location. The problem with systems of this type is that personnel often forget to actuate the switches when they enter or leave the room. As a result, the information provided by the central station is often inaccurate and therefore unreliable.
Radio frequency (RF) and infrared (IR) personnel location systems are also in use. Systems of these types include RF or IR receivers in each room of the ward. Each receiver is interfaced to the central station. Portable transmitters worn by the personnel periodically transmit RF or IR signals characteristic of the persons. When they enter a room, the RF or IR signals are detected by the receivers. The receivers, in turn, provide location information to the central station.
Signals produced by the RF transmitters of these systems have a tendency to be detected by receivers in adjacent rooms. IR transmitters have the opposite problem. The signals transmitted by IR transmitters are very directional, and depending upon the person's orientation, may not be detected by the receiver within the room. In any event, use of either system can result in unreliable indications at the central station.
It is evident that there is a continuing need for improved personnel location identification systems. For convenience and accuracy, the system must operate without any actions on the part of the personnel whose locations are desired to be known. The system must also be able to recognize personnel irrespective of their position or orientation within the room, and be insensitive to personnel in adjacent rooms. Simply put, the system must provide highly accurate information which personnel at the central station can rely upon at critical times.